facilities.md: Add some general DECT/POC information

See merge request !79

facilities.md: Add minimal section on the GSM/cellular networks

See merge request !80

There have been some question about the supported bands and availability
of SIM cards in the matrix chat, so let's add at least that kind of
basic information.

I'm not a POC member, but just adding general knowledge known from prior
events, which is better than an empty section.

remove 4mm for 32a

See merge request !77

Laura main patch 02579

See merge request !74

add power infos from last year and adapt

See merge request !75

add links to other camp web apps

See merge request !72

Make Hub URL absolute, move help and legal notice to quick links, rename parcel to "Getting Stuff there and back"

updating a11y info, adding more links

See merge request !73

hub - clickable urls

See merge request !71

Fix Formatting in accessibility.md

See merge request !69

Added additional sponsor

See merge request !67

Add infodesk matrix channel

See merge request infra/static-pages/camp2023-infos!68

Some small updates to the Network page

See merge request infra/static-pages/camp2023-infos!66

fixing up a few formatting issues

See merge request !65